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Presentation on theme: "What Are Some Properties of Waves"— Presentation transcript:

2 WavesWave: disturbance that travels through matter or space, carrying energy from one place to another without carrying matter with itInformation we receive travels in wavesLight, sound, radio, televisions,Mechanical waves: waves that need matter to travel throughSubstance, matter, only vibrates back & forth or side-to-sideFloating objectBobs up and downDoesn’t move in direction of wavesWaves don’t transport matter, they only transport energy

3 WavesSurface waves in water = combination of motion of two kinds of wavesBack and forth vibrationSide-to-side vibrationResulting motion is circular

4 Waves Crest: highest part of wave Trough: lowest part of waveHeight: vertical distance between crest and troughAmplitude: distance any point on wave is moved from resting positionEqual to ½ heightGreater energy of wave, greater amplitudeMeasured from resting position to crest or trough

5 Waves Wavelength: horizontal distance between one crest and the nextAlways the same in a series of wavesCan be measured between any two identical pointsAmplitude and wavelength of waves can vary greatly

6 Different Kinds of WavesTransverse wave: particles vibrate at right angles to direction of waveYarn moved side-to-sideWaves traveled forwardExamples:Guitar stringLight (Electromagnetic waves)Light doesn’t need a medium, matter, to travel through

7 Different Kinds of WavesLongitudinal wave: particles vibrate back and forth in the same direction as the wave is movingCompressions: areas where particles are closer togetherRarefaction: areas where particles are spread outExamples:Sound wavesMost other waves that travel through liquids or gases

8 Speed, Frequency, and WavelengthThe speed of a wave is always the same in a particular substance, unless there are changes to the substanceSpeed of sound through air always the sameChange temperature – speed changesSpeed of waves through water always the sameChange depth – speed changesSpeed measured by measuring distance a single point, crest or compression, travels in given time

9 Speed, Frequency, and WavelengthFrequency: number of vibrations a wave has in a given timeMeasured by counting number of crests or compressions passing point in certain amount of timeMeasured in units called hertz1 hertz = 1 vibration per second1 crest passes a point in 1 second2 hertz = 2 crests passing in 1 second

11 Energy From WavesAll waves carry energy in the form of: light, sound, heat, or motionLife on Earth depends on waves carrying energy from sunHeats planetAllowing plants to make food

12 Energy From Waves People use energy carried in waves Solar panelsChange sun’s light energy into heat or electricityOcean wavesScientists doing experiments to use energyAdvantages:Renewable sourceWon’t cause pollution from combution

13 Energy From Waves Energy in waves can also destroy Hurricane wavesHuge amounts of energyCause almost as much damage as windsTsunami: waves generated by undersea earthquakes“Tidal waves”Carry greatest amount of energyBegins on ocean floorOn surface it not very noticeableWhen it reaches shore, height may be 35 m (115 ft)

14 Energy From Waves Energy in waves can also destroy EarthquakesSeismic wavesEnergy travels through EarthBoth transverse and longitudinalThird kind of wave on surface, similar to waterGround ripples up and downCircular motion

15 SummaryMechanical waves are disturbances in a substance that carry energy without carrying the substance (matter)Other waves, i.e. light, carry energy without needing matter to travel throughTransverse waves displace particles at right angles to the motion of the waveLongitudinal waves displace particles in the same direction as the waveRelationship – speed = wavelength x frequencySome energy from waves can be used, but the energy in waves can also cause great damage